Consumers are constantly demanding products that meet their daily styling and conditioning needs without damaging the hair. The perceived and sometimes real impact of various treatments and the implements such as blow drying and flat iron can have detrimental effects on the acute and chronic nature of hair.
Permanent methods—or relaxers—usually comprise the steps of applying onto hair a composition comprising a high pH solution (or combination of components to generate high pH), leaving on for a protracted time and then applying a neutralizing composition. A relaxer is a treatment predominately used by people of African-descent to permanently straighten hair. The treatment relies on either the one-step sodium hydroxide (lye) or a two step (e.g. guanidine carbonate and calcium hydroxide) to achieve very high pH (pH 12-14).
Semi-permanent benefits can be achieved using redox chemistry such as thioglycolic acid (TGA) and hydrogen peroxide. Here, the curly hair is transformed into the straight hair because the disulfide bonds are broken by the reaction with TGA. The straighter style is locked in during the oxidation step with hydrogen peroxide.
Non-permanent methods usually comprise the step of heating the hair with a flat-iron or heating element. Methods using such devices in combination with chemically-modifying the internal hair fibres can obtain long-lasting effects e.g. over several months. The Brazilian Keratin Treatments (BKTs) enable the achievement of a straight hairstyle that lasts several months via a shampoo treatment. The key active in BKTs is formaldehyde. The most efficacious treatments (used mainly in salons) rely on high temperature—usually 232° C. (450° F.)—with formaldehyde. Hair treated with products with high concentration of formaldehyde such as Brazilian Blowout delivers semi-permanent straight hair. Over time and following shampooing, the hair reverts back to a curly configuration.
The known methods for straightening hair all have drawbacks. The permanent methods are typically time-consuming and may damage hair. In addition, such methods show little flexibility so that any need and/or wish for changing the hairstyle would require conducting again a “permanent” wave onto hair, which is time-consuming and further damages the hair.
Along with the high potential skin irritation during application, relaxers tend to permanently change the hair by breaking the natural disulfide bonds in the hair. This leaves the hair weaker and more prone for further breakage. Over-processing can also increase hair damage and skin irritation. Consumer products using redox chemistry to achieve semi-permanent benefits, but overprocessing the hair and the strong sulphur smell are concerns of technologies based on reducing chemistry.
According to the US National Toxicology Program, formaldehyde is known to be a human carcinogen. Therefore, providing a semi-permanent style with carcinogen-free formulation is paramount. Given the safety concern of formaldehyde and the damaging effect of relaxers and reducing chemistry, there is a need for a safe alternative to durable straightening that does not break disulfide bonds.
None of the above methods allow achieving a hairstyle that may be retained and/or recovered after at least one shampoo treatment without severely damaging the hair or using a carcinogenic active. There is a need for the provision of a method for achieving a hairstyle that lasts at least five shampoo treatments so that the user would not need to re-shape hair after each shampoo but would still have the opportunity to change hairstyle after some time and without needing to use stringent or harsh hair treatment, such as the permanent technologies outlined above.
There is a need therefore for providing a method for achieving and semi-permanently retaining and/or recovering hairstyle using actives that do not break disulfide bonds (reducing agents) or that are considered carcinogenic. There is also the need for providing a method for obtaining a hairstyle exhibiting resistance to shampoo treatments. Particularly, there is a need for providing a method for retaining and/or recovering hairstyle after at least one shampoo treatment, particularly after five shampoo treatments, more particularly after ten shampoo treatments. In addition, there is a need for providing a method for achieving and retaining and/or recovering hairstyle, without damaging hair. Also, there is a need for providing more economic semi-permanent hair straightening or hair relaxing treatments.